This invention relates to chemical injector control systems and more particularly relates to a control system which may control multiple injectors to a control system which may control multiple injectors injecting multiple chemicals into a common process.
Chemical injection control systems and methods have been known in the art for sometime. Typically, in agricultural chemical injection control systems, two chemical supply tanks are used. Each tank contains a premixed blend of chemicals (typically nutrients or fertilizers). Two tanks are used to separate chemical blends containing chemicals which will not mix or blend together (i.e. will not remain in suspension) or which will undesirably react to one another. A pump (typically a centrifugal pump) and a control valve are provided on an outlet of each chemical supply tank. A downstream sensor is used to send a feedback signal, indicative of the effect of the injected chemicals, to the controller. In typical prior art agricultural systems, the sensor senses conductivity. The controller regulates the flow of chemicals through the pumps and control valves into the process. Normally the chemicals are injected into irrigation water. Shortcomings of the prior systems include: they are feedback systems, i.e., they measure the effect of the injected chemicals on the process before making adjustment; an downstream sensor malfunction may destroy the process; the lag time required for the process to react to the injection chemical and for the downstream sensor to measure the reaction; if a pump or control valve on the outlet on one of the chemical supply tanks fails and shuts off the tank, the controller may open the control valve on the other tank to try to compensate for the demand of the sensor, which will result in overdosing the agricultural process with the chemicals contained in one tank; the user must either mix chemicals into two blends (one blend for each tank) or buy pre-blended chemicals and must use the contents of a tank before changing the blend in the tank, therefore the user cannot change the blend in a tank instantaneously to satisfy the changing needs of an agricultural process.